1. Field of the Invention
The present invention relates to a can seamer in a can filling line, and more particularly to a can seamer provided with means for facilitating replacement of seaming rolls, a seaming chuck and a knock-out pad required as a result of changing the can size, or the like.
2. Description of the Prior Art
At first, the construction and operation of a conventional can seamer in the prior art will be described with reference to FIGS. 11 to 14. FIGS. 11 to 13 illustrate the structure of a seaming chuck and seaming rolls in a can seamer in the prior art. FIG. 11 is a plan view of a seaming mechanism in a conventional rotary seamer, FIG. 12 is a side view of seaming rolls, and FIG. 13 is a vertical cross-sectional view of a seaming mechanism. In these figures, reference numeral 11 designates a first seaming roll, numeral 12 designates a second seaming roll, and numeral 13 designates a seaming chuck. In addition, reference numeral 14 designates a seaming lever inserted around a seaming roll shaft 15 via splines (serrations) 15a, which seaming lever 14 can be extracted downwards, but which is fixed to the shaft 15 so as to be integrally rotatable, therewith. To the lever 14 is fixed a shaft 16. Each of the seaming rolls 11 and 12 is rotatably suspended at the center of the shaft 16 via a bearing 18 fixed to the shaft 16 by means of a screw 17. On the other hand, the seaming chuck 13 is mounted via splines (or serrations) 22 to the bottom end of a rotary cylinder 21, which is rotatably supported from a rotary frame 19 via a bearing 20 so that the seaming chuck 13 can rotate integrally with the same rotary cylinder 21. A knock-out rod 23 extends within the rotary cylinder 21 so as to be slidable in the vertical direction. Reference numeral 27 designates a connecting bracket, ,which integrally connects the seaming lever 14 and the seaming chuck 13. More particularly, the bracket 27 is connected with the seaming chuck 13 via flanges 28 provided along its outer circumference, and is connected with the seaming lever 14 via a ring 29, and this ring 29 is rotatably fixed by means of a lock nut 30 engaged with the connecting bracket 27. In addition, reference numeral 31 designates a bolt for positioning the seaming chuck 13 in the vertical direction with respect to the rotary cylinder 21.
At the time of seaming a can, normally the can exerts a push-up force upon the seaming chuck 13 a push-up force, and the seaming rolls 11 and 12 are also exert a reaction force generated upon pushing a can lid during the operation of seaming a can, and are thus pushed upwards. In addition, in order to prevent the seaming lever 14 from slipping out of the seaming roll shaft 15, a cam 35 rotatable about a shaft 37 mounted to the seaming lever 14 is provided. By rotating a lever 36, the cam 35 is made to enter a notch groove provided on the seaming roll shaft 15 to serve as a stopper.
On the other hand, the top end of the seaming chuck 13 butts against a flange of the rotary cylinder 21, and this rotary cylinder 21 is rigidly supported in the vertical direction with respect to a seamer main body via a bearing 20. Furthermore, with, regard to the structure of the seaming roll shaft 15, for the sake of convenience, description will be made with reference to FIG. 1. Since the seaming roll shaft 15 is pushed upwards by means of a compression spring 43 via a cam lever 39, when the seaming lever 14 supporting the seaming rolls 11 and 12 is fixed to the seaming roll shaft 15, its top end butts against a washer 38 mounted to the rotary frame 19 (shown at E). Also, between the cam lever 39 and the rotary frame 19 is formed a gap space F.
By means of the above-mentioned arrangements, the vertical positions of the seaming chuck 13 and the seaming rolls 11 and 12 can be insured. It is to be noted that in FIG. 1, reference numeral 41 designates a cam follower, numeral 42 designates a seamer main body frame, numeral 42a designates a cam groove, and when a can seaming mechanism rotates as a result of the action of the cam groove 42a and the cam follower 41, the seaming roll shaft 15 rotates, hence the seaming lever 14 swings, and the seaming rolls 11 and 12 alternately perform seaming operations.
Next, description will be made of operations for changing the type of cans. When it is necessitated to replace the seaming rolls 11 and 12 and the seaming chuck 13 in response to a change in can lid diameter, under the condition where a can is not present, the can seamer is rotated to move the seaming rolls up to a position where working is easy, the top end of the seaming roll shaft 15 is depressed by means of a tool, and after a gap space has been formed between the seaming lever 14 and the washer 38, the bolt 31 is loosened. Simultaneously therewith, the cam 35 is disengaged from the notch groove in the seaming roll shaft 15 by turning the lever 36, and the seaming rolls 11 and 12 and the seaming chuck 13 are pulled down, gripped by hands. Then, since the seaming lever 14 and the seaming chuck 13 are integrally connected by the connecting bracket 27, the seaming lever 14 is disengaged from the seaming roll shaft 15 via the splines 15a, and the seaming chuck 13 is disengaged from the rotary cylinder 21 via the splines 22, and they are integrally pulled down via the connecting bracket 27.
Subsequently, when it is intended to mount a seaming lever having seaming rolls of changed sizes and a seaming chuck of a changed size, since the spline diameters are identical to those of the used lever and chuck, after the splines of the seaming lever 14 are aligned with the splines 15a of the seaming roll shaft 15, the splines of the seaming chuck 13 are aligned with the splines 22 of the rotary cylinder 21, and they are pushed in, the seaming chuck 13 is fixed by fastening the bolt 31, the seaming lever 14 is fixed to the seaming roll shaft 15 by turning the lever 36 to insert the cam 35 into the notch groove in the seaming roll shaft 15, and if a depressing force is removed from the top end of the same shaft 15, the mounting work is finished.
Another example of a can seamer in the prior art is seen in Laid-Open Japanese Utility Model Specification No. 54-9137 (1979), and in the following, this will be explained with reference to FIG. 14. In this figure, reference numeral 101 designates seaming rolls, which are rotatably mounted around respective shafts 103 and 104 fixed to a seaming lever 102. Reference numeral 105 designates a seaming chuck, which is threadedly fixed to a bottom end of a rotary cylinder 106, and a knock-out pad 109 is fixed by a screw 108 to the bottom end of a knock-out rod 107 which penetrates through the same rotary cylinder 106 in a vertically slidable manner. This knock-out pad 109 is projectable from a recessed portion 110 at the bottom of the above-mentioned chuck 105. In addition, the upper portion of the above-mentioned knock-out rod 107 is inserted via a ball bearing into a knock-out carrier 112. The knock-out carrier 112 is guided by a knock-out carrier guide 111, and is prevented from rotating by means of an anti-rotation guide pin (not shown) which is parallel to a center axis of the knock-out rod 107. Also, to the knock-out carrier 112 is mounted a cam follower 113, and provision is made such that when the can seamer is operated the cam follower 113 may move up and down following a profile of a 114 cam groove and the movement may be transmitted via the ball bearing to the knock-out rod 107. Parallel twin faces for engagement with a spanner are machined on a shaft 107a at the top of the knock-out rod 107.
In order to remove the knock-out pad 109 from the knock-out rod 107 for the purpose of changing the type of knock-out pad as a result of the change of can sizes, the screw 108 is loosened while the top shaft 107a of the knock-out rod 107 is held by means of a spanner, the screw 108 is loosened, and thereby the knock-out pad 109 is removed. When a knock-out pad to be replaced is mounted, it is only necessary to perform the above-mentioned steps of operation in the reverse sequence.
As will be seen from the above description, the type-changing work at the time of changing can sizes in the can seamer in the prior art as shown in FIGS. 11 to 13 has a shortcoming in that it necessitates a lot of time and labor because of the fact that a manually operated handle was used for rotating a seaming mechanism, and at the time of replacement of seaming rolls the top end of a seaming roll shaft had to be held by means of a hand tool.
In addition, mounting of a seaming lever and positioning in the vertical direction in the heretofore known can seamer as shown in FIGS. 11 to 13 relied upon the method of aligning a horizontal notch groove cut in a seaming roll shaft with a cam 35 provided on a seaming lever and fixing them by inserting the cam plate into the notch groove with such a structure, a lot of time is needed to adjust a clearance in the vertical direction of the seaming roll shaft when can sizes are changed. Explaining the reasons, a seaming chuck is spinning at a high speed and also is making rotary movement at a high speed along a circumference as accompanied by seaming rolls, and so if the clearance in the vertical direction of the seaming roll shaft should deviate from a predetermined tolerable value, baking would arise or unacceptable seaming, caused by vibrations, would occur. Therefore, in a seaming process between a can and a can lid, the seaming chuck pressing the can lid and the seaming roll for carrying out seaming would necessitate a high precision in positioning. However, in the seaming lever mounting structure in the prior art, clearance adjustment involved problems such as requiring a lot of labor and time because each time the seaming lever must be extracted from the seaming roll shaft to replace or grind a shim.
Also, in the heretofore known apparatus shown in FIG. 14, since there are many seaming chucks mountable on a single seamer, if it is intended to replace the knock-out pad, each time the top end 107 the of a knock-out rod must be restrained by means of a spanner and the knock-out pad 109 must be disengaged by releasing the screw 108, and so there is a problem in that a lot of labor and time were necessitated for mounting and dismounting of the pad.